US

Dan LaMoore wheels a clock away from the test area as it is prepared to be shipped to a Tennessee school at the Electric Time Company in Medfield, Massachusetts.

Charles Krupa/AP

Dan LaMoore wheels a clock away from the test area as it is prepared to be shipped to a Tennessee school at the Electric Time Company in Medfield, Massachusetts.

Democratic presidential candidate Hillary Clinton speaks to an overflow crowd during a campaign event in Vernon Hills, Illinois.

Justin Sullivan/Getty Images

Democratic presidential candidate Hillary Clinton speaks to an capacity audience during a campaign event in Vernon Hills, Illinois.

Tim Ferris shades himself from the sun while waiting in line to attend a campaign rally with Democratic presidential candidate, Sen. Bernie Sanders, in Kissimmee, Florida, USA

Phelan M. Ebenhack/AP

Tim Ferris shades himself from the sun while waiting in line to attend a campaign rally with Democratic presidential candidate, Sen. Bernie Sanders, in Kissimmee, Florida, USA

Marco Rubio...Republican presidential candidate, Sen. Marco Rubio, R-Fla., poses for photographs during a campaign rally in Hialeah, Fla., Wednesday, March 9, 2016. (AP Photo/Paul Sancya)

Paul Sancya/AP

Republican presidential candidate, Senator Marco Rubio, poses for photographs during a campaign rally in Hialeah, Florida 

Barack Obama...President Barack Obama meets with members of his economic team in the Roosevelt Room of the White House in Washington, Friday, March 4, 2016. Obama spoke about U.S. employers adding 242,000 workers in February, driving another solid month for the resilient American job market.

Pablo Martinez Monsivais/AP

President Barack Obama meets with members of his economic team in the Roosevelt Room of the White House in Washington. Obama spoke about U.S. employers adding 242,000 workers in February, driving another solid month for the resilient American job market 

Oklahoma City Thunder's Kevin Durant drives to the basket between Golden State Warriors' Harrison Barnes, left, and Shaun Livingston during the second half of an NBA basketball game in Oakland, Calif.

Marcio Jose Sanchez/AP

Oklahoma City Thunder’s Kevin Durant drives to the basket between Golden State Warriors’ Harrison Barnes, left, and Shaun Livingston during the second half of an NBA basketball game in Oakland, Calif.

The plane carrying Expedition 46 Commander Scott Kelly of NASA is seen as it taxis after landing at Ellington Field after his return to Earth

Joel Kowsky/NASA via Getty Images

The plane carrying Expedition 46 Commander Scott Kelly of NASA is seen as it taxis after landing at Ellington Field after his return to Earth

Elise Amendola/AP

Voters cast ballots at a polling station for Massachusetts’ primary election, as Super Tuesday starts in North Andover, Mass USA

Hillary Clinton...Democratic presidential candidate Hillary Clinton gestures during a commercial break at a CNN town hall style televised event at the University of South Carolina School of Law, in Columbia, S.C., Tuesday, Feb. 23, 2016. (AP Photo/Gerald Herbert)

  © Gerald Herbert/AP

Democrat presidential candidate Hillary Clinton gestures during a commercial break at a CNN town hall televised event at the University of South Carolina School of Law, in Columbia, US

Protesters carry placards outside an Apple store

Steven Senne/AP

Protesters carry placards outside an Apple store in Boston to protest the FBI obtaining a court order that requires Apple to make it easier to unlock an encrypted iPhone used by a gunman in December’s shooting in San Bernardino

Julio Cortez / AP Photo

A full moon rises over the Statue of Liberty, seen from the Port Liberte neighborhood of Jersey City, N.J

Mike Nelson / EPA

Supporters of US Republican presidential candidate businessman Donald Trump at a rally in Las Vegas, Nevada

Mario Anzuoni/Reuters

  

Demonstrators protesting for an increase in the minimum wage enter the media file center at the PBS NewsHour Democratic presidential candidate debate at the University of Wisconsin-Milwaukee

Win McNamee/Getty Images

Demonstrators protesting for an increase in the minimum wage enter the media file center at the PBS NewsHour Democratic presidential candidate debate at the University of Wisconsin-Milwaukee

President Barack Obama returns a salute as he boards Air Force One before his departure from Andrews Air Force Base, Maryland. USA

Pablo Martinez Monsivais/AP

President Barack Obama returns a salute as he boards Air Force One before his departure from Andrews Air Force Base

Win McNamee/Getty

Democratic presidential candidate, Sen. Bernie Sanders addresses supporters after winning the New Hampshire Democratic primary in Concord, New Hampshire. Sanders defeated Democratic presidential candidate Hillary Clinton in the first-in-the-nation primary

New Hampshire Residents Vote In The First-In-The-Nation New Hampshire Primary...A resident, right, hands an election official a Republican ballot at the town hall polling site during the New Hampshire presidential primary election in Harts Location, New Hampshire, U.S., on Tuesday, Feb. 9, 2016. According to the New Hampshire Secretary of State's office, the state has 383,834 voters who haven't declared a party affiliation, compared to 260,896 registered Republicans and 229,202 Democrats. Photographer: Andrew Harrer/Bloomberg

Andrew Harrer/Bloomberg

A resident, right, hands an election official a Republican ballot at the town hall polling site during the New Hampshire presidential primary election in Harts Location, New Hampshire, U.S., on Tuesday. According to the New Hampshire Secretary of State’s office, the state has 383,834 voters who haven’t declared a party affiliation, compared to 260,896 registered Republicans and 229,202 Democrats.

Presidential Candidate Marco Rubio Holds Retail Campaign Stops...An image of Senator Marco Rubio, a Republican from Florida and 2016 presidential candidate, is seen on his campaign bus as it sits outside the building which houses his campaign headquarters in Manchester, New Hampshire, U.S., on Monday, Feb. 8, 2016. Rubio, who surged to second place in polls after coming in third in the Iowa caucuses, spent Sunday trying to extinguish a political brushfire after he delivered the same canned answer three times within a matter of minutes at Saturday's presidential debate. Photographer: Daniel Acker/Bloomberg

Daniel Acker/Bloomberg

An image of Senator Marco Rubio, a Republican from Florida and 2016 presidential candidate, is seen on his campaign bus as it sits outside the building which houses his campaign headquarters in Manchester, New Hampshire, U.S 

Marco Rubio Campaigns Ahead Of New Hampshire Primary...NASHUA, NH - FEBRUARY 08:  Republican presidential candidate Sen. Marco Rubio (R-FL) sips coffee before doing a television interview at Norton's Classic Cafe during a campaign stop February 8, 2016 in Nashua, New Hampshire. Rubio is hoping for a good showing on Tuesday when people in New Hampsire head to the polls in the 'First in the Nation' presidential primary.  (Photo by Chip Somodevilla/Getty Images) **BESTPIX**

Chip Somodevilla/Getty

Republican presidential candidate Sen. Marco Rubio sips coffee before doing a television interview at Norton’s Classic Cafe during a campaign stop in Nashua, New Hampshire

Protected by a mosquito net, Nadia Gonzalez recovers from a bout of dengue fever at a hospital in Luque, Paraguay Friday, Feb. 5, 2016. Dengue, like the Zika virus, is transmitted by the same vector, the Aedes aegypti mosquito. Zika was discovered in a Ugandan forest in 1947 and until last year, the virus had never caused serious disease. It has now spread to more than 20 countries. (AP Photo/Jorge Saenz)

Jorge Saenz/AP

Protected by a mosquito net, Nadia Gonzalez recovers from a bout of dengue fever at a hospital in Luque, Paraguay. Dengue, like the Zika virus, is transmitted by the same vector, the Aedes aegypti mosquito